After boarding the United plane everyone was settled in (we are a family of 3, including my mother who is 72 years of age).
Announcement stated that the plane battery had to be replaced, everyone had to get out.
Waited 3 hours to be told the flight is cancelled.
Waited 2 hours in line to reschedule flight and organise a hotel room.
At this point we were without sleep or food for 24 hours, as United did not serve food in the 2 flights to get to L.A., and told they did not have any food available for purchase from the menus.

Flight cancellations happen, we understand that and are grateful that the plane was checked for deficiencies.

This is why we will never fly with United again:

We were told to wait for the Baymont hotel shuttle outside.
Collected luggages and waited 1.5h for the shuttle, only to find out by other United staff that the Baymont hotel does not provide shuttles. Organised a private shuttle to Baymont.
Arrived at Baymont hotel, told NO rooms were available, United had overbooked.
United were not answering phones.
No taxis were available.
Had to WALK WITH LUGGAGES to nearest hotel to try to find rooms at 5am in L.A., whilst being extremely exhausted and hungry, and concerned for my family's welfare.
I now have a shoulder injury due to this not to mention the stress of the experience.

HOW can UNITED give us instructions that were so WRONG.
They've apologised for the flight cancellation but have not acknowledged that giving people wrong instructions, causing undue stress, is completely negligent.